Richard Upton of Australia, a member of the silver medal winning 4x100 free relay at the recent World Championships in Perth has tested positive for a banned substance.

The positive test was detected during a random drug test on Feb. 17 in Australia. The substance was identified as probenicid, which can be used as a masking agent for steroids. It is also used by doctors to help patient's retain penicillin when combating infections.

Upton reported that he had been prescribed the probenicid by his family doctor days before the drug test to help him fight a chest infection.

A number of participants and journalists came down with flu and chest infections during and following the World Championships in Perth.